The prior art describes methods of creating diversity by recombination of DNA sequences encoding two or more polypeptides, followed by transformation of a suitable host organism with the recombined DNA sequence and screening of the transformants for enzymatic activity. The recombination may be random or directed. WO 1995022625; U.S. Pat. No. 6,368,805; J. E. Ness et al., Nature Biotechnology, vol. 20, December 2002, pp. 1251-1255; M. C. Saraf et al., 4142-4147, PNAS, Mar. 23, 2004, vol. 101, No. 12.